Temporal Variability of Nonlinear Wave Processes during Different Sudden Stratospheric Warming Types

Abstract In winter, planetary-scale atmospheric waves play the main role in the formation of atmosphere conditions, and a polar vortex forms in the stratosphere. Sudden stratospheric warming (SSW) is a striking example of the interannual variability of the stratospheric polar vortex caused by stationary planetary waves. SSW significantly affects the entire middle atmosphere, ionosphere, weather conditions in the troposphere, and occurrence of extreme weather events. Based on MERRA-2 reanalysis data, this work analyzes the internal dynamics of a major SSW accompanied by stratospheric polar vortex (SPV) displacement and splitting. Nonlinear interactions of planetary waves with each other and with the mean flow are explicitly calculated with the aim of identifying similar trends in origination of different SSW types. It is shown that the occurrence of a SSW with SPV splitting is not always be accompanied by variations in the activity of stationary planetary wave with zonal wavenumber 2 (SPW2), but is determined by the maximal interactions of SPW2 with the mean flow. For SSW with SPV displacement, wave–wave interactions during the generation of secondary stationary planetary wave with zonal wavenumber 1 (SPW1) are shown to be maximal 1–2 weeks before a SSW, and during the generation of secondary SPW2, 5–10 days before a SSW with SPV displacement. The results are important for identifying SSW predictors.